title: A microfluidic approach to synthesizing high-performance microfibers with tunable anhydrous proton conductivity.
abstract: Here, we demonstrate a new approach for the synthesis of ion exchange microfibers with finely tuned anhydrous conductivity. This work presents microfluidics as a system to control the size and phosphoric acid (PA) doping level of the polybenzimidazole (PBI) microfibers. It has been shown that the PA doping level can be controlled by varying the flow ratios in the microfluidic channel. The diameter of the microfibers increased with extending mixing time, whereas the doping level decreased with increasing flow ratio. The highest doping level, 16, was achieved at the flow ratio of 0.175. The anhydrous proton conductivity of the microfibers was found to be adjustable between 0.01 and 0.1 S cm(-1) at 160 °C, which is considerably higher than for conventionally doped PBI cast membranes (0.004 S cm(-1)). Furthermore, molecular dynamic simulation of proton conduction through the microfibers at different doping levels was in good agreement with the experimental results. These results demonstrate the potential of the microfluidic technique to precisely tune the physicochemical properties of PBI microfibers for various electrochemical applications such as hydrogen sensors, fuel cells as well as artificial muscles.
authors.affiliation: Laboratoire de Microsystemes (LMIS4), Institute of Microengineering, École Polytechnique Fédérale de Lausanne (EPFL), Station 17, CH-1015 Lausanne, Switzerland. jules.vandersarl@epfl.ch philippe.renaud@epfl.ch.
authors.forename: Mohammad Mahdi
authors.initials: MM
authors.lastname: Hasani-Sadrabadi
authors.forename: Jules J
authors.initials: JJ
authors.lastname: VanDersarl
authors.forename: Erfan
authors.initials: E
authors.lastname: Dashtimoghadam
authors.forename: Ghasem
authors.initials: G
authors.lastname: Bahlakeh
authors.forename: Fatemeh Sadat
authors.initials: FS
authors.lastname: Majedi
authors.forename: Nassir
authors.initials: N
authors.lastname: Mokarram
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bertsch
authors.forename: Karl I
authors.initials: KI
authors.lastname: Jacob
authors.forename: Philippe
authors.initials: P
authors.lastname: Renaud
mesh_terms: D055664:Electrochemical Techniques; D006859:Hydrogen / Q000032:analysis; D006860:Hydrogen Bonding; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D010756:Phosphoric Acids / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011522:Protons; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D010756:Phosphoric Acids; D011108:Polymers; D011522:Protons; D014867:Water; D006859:Hydrogen; C030242:phosphoric acid